text: The INEPT signal enhancement has two sources:
  * The spin population effect increases the signal by a factor of K = ratio of gyromagnetic ratios γ/γ of the nuclei,  where γ and γ are the gyromagnetic ratio of the proton (the I spins) and the low-sensitivity nuclei (the S spins) respectively.
  * Nuclei with higher magnetogyric ratio generally relax more quickly.  Since the rate at which the INEPT transfer can be repeated is limited by the relaxation of these spins (rather than the low sensitivity spins), the INEPT experiment can be repeated more frequently, increasing the signal-to-noise ratio.
  As a result, INEPT can enhance the NMR signal by a factor larger than K, while the maximum enhancement via NOE is by a factor of 1+K/2.  Unlike with NOE, no penalty is incurred by a negative gyromagnetic ratio in INEPT. It is therefore a useful method for enhancing the signal from nuclei with negative gyromagnetic ratio such as N or Si.  The N signal may be enhanced by a factor of 10 via INEPT.